Display apparatuses such as liquid crystal display apparatuses and organic light-emitting diode display apparatuses have been widely used. Liquid crystal display apparatuses and organic light-emitting diode display apparatuses use thin film transistor (TFT) to control pixels in the display panel. Examples of TFT include amorphous silicon TFT, polycrystalline silicone TFT, single crystal silicon TFT, and metal oxide TFT.